<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        #chat{
            width: 300px;
            height: 300px;
            background-color: orange;
            position:fixed;
            right: 0;
            bottom: 0;
        }
        #main{
            width: 100%;
            height: 1000px;
            background-color: pink;
        }
    </style>
</head>
<body>
    <div id="chat"></div>
    <div id="main"></div>
</body>
</html>